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71.
Peter Brodelius Kjell Nilsson Klaus Mosbach 《Applied biochemistry and biotechnology》1981,6(4):293-307
Whole cells ofTrigonopsis variabilis were immobilized by entrapment in Ca2+-alginate and used for the production of α-keto acids from the corresponding D-amino acids. The D-amino acid oxidase within
the immobilized cells has a broad substrate specificity. Hydrogen peroxide formed in the enzymatic reaction was efficiently
hydrolyzed by manganese oxide co-immobilized with the cells. The amino acid oxidase activity was assayed with a new method
based on reversed-phase HPLC. Oxygen requirements, bead size, concentration of cells in the beads, flow rate, and other factors
were investigated in a “ trickle-bed ” reactor. 相似文献
72.
Dmitry A. Zyuzin Svetlana V. Cherepanova Elena B. Burgina Victor G. Kostrovskii 《Journal of solid state chemistry》2006,179(10):2965-2971
Genesis of the structure of zirconia particles prepared by precipitation of amorphous hydrated zirconia by ammonia from the ZrO(NO3)2 solution followed by a mild hydrothermal treatment (HTT) of precipitate, washing and calcination under air up to 1000 °C has been studied by X-ray diffraction (XRD), Raman and FTIRS. As revealed by FTIRS of lattice modes, the local structure of amorphous zirconia subjected to HTT is close to that in m-ZrO2. This helps to obtain nearly single-phase monoclinic nanozirconia (particle size 5-15 nm) already after a mild calcination at 500 °C. Stability of this phase with nanoparticles sizes below the critical value determined by thermodynamic constraints is due to its excessive hydroxylation demonstrated by FTIRS. Dehydroxilation and sintering of these nanoparticles at higher (600-650 °C) temperatures of calcination leads to reappearance of the (111) “cubic” reflection in XRD patterns. Modeling of XRD patterns revealed that this phenomenon could be explained by polysynthetic (001) twinning earlier observed by HRTEM. 相似文献
73.
We have evaluated the potential of near-infrared spectroscopy (NIRS) as a technique for rapid analysis of lactate in whole blood. To test the NIRS technique, a comparison was made with a standard clinical method using whole blood samples taken from five exercising human subjects at three different stage of exercise. To expand lactate concentration within the physiological range, standard additions method was used to generate 45 unique data points. Spectra were collected over the 2050-2400 nm spectral range with a 1 mm optical path length quartz cell. Reference lactate concentrations in the samples were determined by enzymatic measurements. Estimates and calibration of the lactate concentration with NIRS was made using partial least squares (PLS) regression analysis and leave-N-out cross validation on second derivative spectra. Separate calibrations were determined from each of the subject samples and cumulative PRESS was used to determine the number of PLS factors in the final model. The results from the PLS model presented are generated from the five individual calibration coefficient vectors and provided a correlation coefficient of 0.978 and a standard error of cross validation of 0.65 mmol l−1 between the enzymatic assay and the NIRS technique. To study the parameters that impact the spectra baseline and the correlation between the calculated model and the data, referenced measurements of lactate against baseline spectrum were made for each individual. A correlation coefficient of 0.992 and a standard error of cross validation of 0.21 mmol l−1 were found. The results suggest that NIRS may provide a valuable tool to assess physiological status for both research and clinical needs. 相似文献
74.
Tomohisa?Yamaguchi Keisuke?Kimura Akira?Tsuchida Tsuneo?OkuboEmail author Mitsuhiro?Matsumoto 《Colloid and polymer science》2005,283(10):1123-1130
Macroscopic and microscopic dissipative structural patterns formed in the course of drying the fractionated and monodisperse bentonite particles (plate-like in their shape) in aqueous deionized suspension and in the presence of NaCl have been studied on a cover glass. The patterns coexisted with the broad ring of the hill accumulated with the particles and with the round hills are formed around the outside edges of the film and in the center, respectively, in the macroscopic scale. By the addition of NaCl the pattern shifts from the broad ring to the round hill in the center. The spoke-like cracks, which have been observed for the suspensions of the spherical particles so often hitherto, are not observed at all for the bentonite suspensions. The characteristic convection flow of the particles and the interactions among the particles and substrate are important for the macroscopic pattern formation. Wrinkled, branch-like and/or star-like fractal patterns are observed in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the particles and/or between the particle and the substrate in the course of drying. 相似文献
75.
Lifang Yang Haifeng He Hongqing Cao Xinhua Wan Qi-feng Zhou Department of Polymer Science & Engineering College of Chemistry & Molecular Engineering Peking University Beijing China 《高分子科学》2002,(5):401-407
Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl toquinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M_w ca. 750) as flexible segments, were synhesized. Thechemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by ~1H-NMR and MALDI-TOF mass spectromeny. The diblock oligomers showed good solubility in common organic solvents and aggregated in wateras characterized by a blue shift in UV-vis absorption spectra, a red shift in emission spectra, quenching of the fluorescenceand formation of the microfibrilla and fractal-like structures. The formation of different supramolecular structures meant thatthis effort might lead to commercial important highly organized functional materials. 相似文献
76.
Principal oscillation pattern (POP) analysis was recently introduced into climatology to analyze multivariate time series xi(t) produced by systems whose dynamics are described by a linear Markov process x=Bx + . The matrixB gives the deterministic feedback and is a white noise vector with covariances (t)
j
(t*Q
ij
(t–t. The POP method is applied to data from a direct simulation Monte Carlo program. The system is a dilute gas with 50,000 particles in a Rayleigh-Bénard configuration. The POP analysis correctly reproduces the linearized Navier-Stokes equations (in the matrixB) and the stochastic fluxes (in the matrixQ) as given by Landau-Lifschitz fluctuating hydrodynamics. Using this method, we find the Landau-Lifschitz theory to be valid both in equilibrium and near the critical point of Rayleigh-Bénard convection. 相似文献
77.
Yasufumi Otsubo 《Journal of colloid and interface science》1997,190(2):466
For electrorheological (ER) suspensions, the aggregate structures of particles were observed in electric fields by the use of transparent cells with different electrode patterns. Although the suspension is dispersed to noninteracting particles without electric fields, many aggregates are formed on the electrode surface in electric fields. Since the dipole–dipole interactions cause chain structures of particles and equilibrium conformations of chains are always aligned with electric field, the aggregates indicate the presence of columns spanning the electrode gap. The particle concentration in columns which are developed between parallel-plate electrodes is about 22 vol %. In striped electrodes, the particles construct striped aggregates along the electrodes and no particles remain in the insulating region. The particle concentration in striped aggregates is about 35 vol %. The nonuniformity of electric field is responsible for the high particle concentration. The increase in particle concentration of column lead to the high yield stress of electrified suspension. Therefore, the ER performance of suspension as an overall response can be improved by the electrode design. 相似文献
78.
利用双光束电子散斑干涉法(ESPI)对试件受热变形进行了实时观测,针对一次实验过程中得到的图片较多(300~500幅)的特点,在图像处理时摒弃了以往的手动识别等位移线的办法,用MATLAB语言编写了批处理程序,能够在采集的大量散斑图片中自动快速准确地标定等位移线,得到相应的位移和应变,并结合实时测量的温度值,获得了45钢和LY12铝合金在不同温升率下的热膨胀系数及其随温度的变化。实验结果表明,在涉及的温升率范围内,温升率的改变对材料热膨胀系数的影响不明显,材料的热膨胀系数随温度的升高略有上升。 相似文献
79.
许多标准和公开出版物中都用双指数函数描述高空核电磁脉冲典型波形。通过数值方法,研究了双指数函数一项重要的性质。根据该性质,详细讨论了高空核电磁脉冲模拟波形数值拟合中,双指数函数特征参数与脉冲峰值、前沿、后沿以及半宽等物理参数的关系,从而提出一种简单有效的脉冲参数计算方法。通过IEC标准中规定的高空核电磁脉冲参数的估计与一个实测高空核电磁脉冲模拟波形的数值拟合,验证了该方法的有效性和可靠性。该方法能够适应多种峰值、前沿和半宽的高宽核电磁脉冲模拟波形的数值拟合。 相似文献
80.